Looking for suggestions for good day trips that one can make from Istanbul. Extra points for any that can be accomplished by public transit (because I have been in a car in Istanbul before, and I was VERY glad I was not driving it).
For context: we have been to Turkey before -- in fact, we were in Turkey in the winter of 2020 when the pandemic blew up, and we had to cut short our trip and scramble a bit to come home early (we spent about 3 weeks prior to that driving from Izmir around to Antalya, flew to Cappadocia, then flew to Istanbul where we HAD planned to spend 4 or 5 days). Sadly, I had brilliantly planned to END our trip in Istanbul, and it was the end of our trip that got lopped off in all the pandemic scramble. We only had one day in Istanbul, and it was a rainy, stormy day at that, so we only got a fleeting taste of the city. Of course, we vowed to return.
I've got a potential trip planned to Malta for next October, with a 4 or 5 day stop in Istanbul on the way in. With 4 or 5 days, I figure we can get to most of the things we missed in Istanbul last time, and maybe have time for a day trip or two out of the city. I'm looking for options for that. I'll rent a car if it's really necessary (I've driven in some pretty chaotic places) but prefer not to if good stuff can be accessed by public transit. Any suggestions? Thanks.